Spread the mustard on each half of the roll. Layer one half of the roll with the pork, ham, cheese and pickles. Top with the remaining half of roll. Spread the butter in a skillet over medium-high heat. Put the sandwich in the middle of the skillet and weigh it down with a cast-iron skillet and cook, turning once, until the bread is lightly browned and the cheese is melted. (Or heat a panini maker or sandwich press and butter each side of the press. Place the sandwiches inside, press down and grill until the cheese is melted and the bread is flat and browned, about 10 minutes.)